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Heat transfer fluid comprising difluoromethane and carbon dioxide

a technology of difluoromethane and carbon dioxide, which is applied in the direction of detergent compositions, chemistry apparatus and processes, detergent materials, etc., can solve the problems of difficult to achieve the combination of characteristics, and achieve the effects of low toxicity, low cost, and low cos

Inactive Publication Date: 2007-07-03
HONEYWELL INT INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0006]Applicants have discovered heat transfer fluids which possess a highly desirable and unexpectedly superior combination of properties, and heat transfer systems and methods based on these fluids. In preferred embodiments, the fluids of the present invention possess properties that have heretofore been associated with CECs, including chemical stability, low toxicity, non-flammability, and efficiency in-use, while at the same time substantially reducing or eliminating the deleterious ozone depletion potential of such refrigerants. In addition, the preferred embodiments of the present invention provide ref rigerants which also substantially reduce or eliminate the negative global warming effects associated with previously used heat transfer fluids. This difficult to achieve combination of characteristics is important, for example, in low temperature air conditioning, refrigeration and heat pump applications.

Problems solved by technology

This difficult to achieve combination of characteristics is important, for example, in low temperature air conditioning, refrigeration and heat pump applications.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0023]A heat transfer fluid consisting essentially of 50% by weight of HFC-32 and 50% by weight of CO2 was tested in accordance with the procedure outlined in Example 1 of U.S. Pat. No. 5,744,052 (hereafter the '052 patent). The resulting vapor pressures was measured at 25° C. and found to be as follows:

[0024]

Wt. % EvaporatedVapor Pressure @ 25° C.0577 psia (3976 kPa)50478 psia (3295 kPa)

This large change (21 relative %) in vapor pressure with amount of fluid vaporized establishes that the heat transfer fluid of the present invention is non-azeotrope-like, which is in contrast to the compositions described in column 3, line 5, of the '052 patent. In addition, this result demonstrates that the present heat transfer fluids possess a vapor pressure, even after a 50% evaporation rate, that is almost twice that of the fluids disclosed '052 patent.

example 2

[0025]Various heat transfer fluids consisting essentially of HFC-32 and CO2 were tested for vapor pressure at 40° F. for comparison to the vapor pressure of HCFC-22 at 40° F., that is, 83 psia. This is the equivalent vapor pressure claimed for the ternary blends described U.S. Pat. No. 5,736,063. The vapor pressure results are reported below:

[0026]

Wt. % HFC-32Vapor Pressure @ 40 F.60251 psia50288 psia40328 psia30378 psia

This example shows that heat transfer fluids in accordance with the present invention have vapor pressures that are 3 to 5 times higher than HCFC-22.

example 3

[0027]This example shows advantages of the present heat transfer fluids relative to HFC-32 as a single component heat transfer fluid. Flammability of refrigerant gases can be determined by preparing various compositions and testing them by the ASTM E-681 method published by the American Society for Testing of Materials, which is incorporated herein by reference. HFC-32 is known to be a flammable gas and precludes its use as a single component refrigerant in many important applications. Applicants have tested various combinations of HFC-32 and CO2 and discovered that the maximum amount of the HFC-32 that can be present in heat transfer fluid blend consisting essentially of CO2 and HFC-32 while remaining nonflammable in all proportions in air (as determined by ASTM E-681) is about 55 mol % (59 wt %). In other words, applicants have discovered that heat transfer fluids of the present invention containing at least 45 mol % (about 40 wt %) CO2, and preferably no more than 55 mol % (about...

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PUM

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Abstract

Disclosed are heat transfer fluids which possess a highly desirable and unexpectedly superior combination of properties, and heat transfer systems and methods based on these fluids. The heat transfer fluid comprise from about 30 to about 70 percent, on a molar basis, of carbon dioxide (CO2) and from about 30 to about 70 percent, on a molar basis, of hydrofluorocarbon (HFC), preferably HFC having one to two carbon atoms, and even more preferably difluoromethane (HFC-32). The preferred fluids of the present invention have a vapor pressure of at least about 100 psia at 40° F. and are also preferably not azeotropic.

Description

FIELD OF THE INVENTION[0001]This invention relates to heat transfer fluids, and in particular heat transfer fluids containing difluoromethane and carbon dioxide.BACKGROUND OF THE INVENTION[0002]It is desirable in many different situations to selectively transfer heat between a fluid and a body to be cooled or warmed. As used herein, the term “body” refers not only to solid bodies but also other fluid materials which take the shape of the container in which they exist.[0003]One well known system for achieving such transfer of heat achieves cooling of a body by first pressurizing a vapor phase heat transfer fluid and then expanding it through a Joule-Thomson expansion element, such as a valve, orifice, or other type of flow constriction. Any such device will be referred to hereinafter simply as a Joule-Thompson “expansion element,” and systems which use such an element are sometimes referred to herein as Joule-Thompson systems. In most Joule-Thomson systems, single component, non-idea...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): C09K5/04
CPCC09K5/045
Inventor SINGH, RAVJIV R.PHAM, HANG T.PAONESSA, MARTIN R.
Owner HONEYWELL INT INC
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